scholarly journals Effect of radial temperature profiles on yields in steam cracking

AIChE Journal ◽  
2004 ◽  
Vol 50 (1) ◽  
pp. 173-183 ◽  
Author(s):  
K. M. Van Geem ◽  
G. J. Heynderickx ◽  
G. B. Marin
Keyword(s):  
Temperature Profiles ◽  
Radial Temperature ◽  
Steam Cracking

Simultaneous Measurements of Droplet Size, Temperature, and Velocity Using an Integrated Phase-Doppler/Rainbow Thermometer

2001 ◽  
Author(s):  
Matt O’ Donnell ◽  
Sumanta Acharya
Keyword(s):  
Refractive Index ◽  
Detailed Examination ◽  
Temperature Profiles ◽  
Droplet Temperature ◽  
Radial Temperature ◽  
Temperature Correlation ◽  
Simultaneous Measurements ◽  
Laser Diagnostic ◽  
The Mean ◽  
And Performance

Abstract This work summarizes efforts to determine the accuracy and performance characteristics of a new and novel laser diagnostic to measure instantaneous, in flight, droplet temperatures. The instrument uses the location of the rainbow peak to deduce the refractive index of the droplet, which in turn is related to the droplet temperature. Preliminary experiments were undertaken in order to understand the fundamental operating principles and limitations of the instrument. These experiments measured the temperature of an isothermal, single stream of monodisperse droplets. These measurements indicate that the mean refractive index can be measured with a standard deviation as low as 0.0001m. Once the operation of the refractometer was proved under isothermal conditions, the measurement of droplet temperatures in a swirl-stabilized combustor was performed. These measurements indicate that the strength of the rainbow signal is significantly hampered by the noise induced by the flame. Preliminary temperature measurements with the combustor equipped with 45° vanes showed relatively constant radial temperature profiles (∼55–60°C) at locations less than 2 inches from the nozzle exit. A detailed examination of the temperature correlation with velocity and diameter revealed that larger and faster moving droplets dominate the distributions. Thus, the smaller droplets that are suspected of having the highest temperatures are inadequately represented in the mean droplet temperature.

Angular and radial temperature profiles in the thermal decomposition of wood

1992 ◽  
Vol 200 ◽  
pp. 401-411
Author(s):  
Rafael Bilbao ◽  
María Benita Murillo ◽  
Angela Millera
Keyword(s):  
Thermal Decomposition ◽  
Temperature Profiles ◽  
Radial Temperature

scholarly journals Development of A Mechanical Setup With Sensors to Determine Interfacial Phenomena Between Supersonic Steam Jet and Water

2020 ◽  
Author(s):  
Afrasyab Khan ◽  
Khairuddin Sanaullah ◽  
Spiridonov Evgeny Konstantinovich ◽  
Darya Khabarova Fedorovna ◽  
Andrew Ragai Henry Rigit ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Water Temperature ◽  
Vessel Wall ◽  
Supersonic Nozzle ◽  
Temperature Sensors ◽  
Interfacial Phenomena ◽  
Temperature Profiles ◽  
Surrounding Water ◽  
Radial Temperature ◽  
First Time

Abstract A specially configured mechanical setup with sensors which was designed to record minimal and increased fluctuations in temperature as evidence of Kelvin–Helmholtz (KH) instabilities by means of LM35 sensors and data acquisition. The generation and spread of KH instabilities in steam and water was accomplished first time by following temperature profiles around the steam’s jet interface with the surrounding water. The supersonic steam was driven into the water in a vessel by means of a specially designed supersonic nozzle at pressure changing from 1.5 to 3.0 bars. Whereas, the temperature of the water in the cylindrical column varied from 30 o C to 60 o C with a change of 5 o C each time when the measurements were performed. The acquisition setup was able to record temperatures across the steam jet in the vessel at a rate of 1 ms, and it could also provide the temperature readings within the vessel. Axial and radial temperature profiles being obtained from 6 temperature sensors positioned along the steam jet, revealed the instabilities being occurred across the interface among the steam and the water, the instabilities spread along the axis towards the vessel wall. However, these instabilities were influenced considerably due to the variation in water temperature in the column, along with change in steam’s pressure. Also, instabilities were affected as well due to the change in viscosity of water owing to change in its temperature.

Numerical Simulations and Experimental Characterization of Heat Transfer From a Periodic Impingement of Droplets

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Mario F. Trujillo ◽  
Jorge Alvarado ◽  
Eelco Gehring ◽  
Guillermo S. Soriano
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Distribution ◽  
Numerical Simulations ◽  
Droplet Impact ◽  
Numerical Comparison ◽  
Temperature Profiles ◽  
Conductive Heat ◽  
Radial Temperature ◽  
The Impact

In this combined experimental and simulation investigation, a stream of HFE-7100 droplets striking a prewetted surface under constant heat flux was studied. An implicit free surface capturing technique based on the Volume-of-Fluid (VOF) approach was employed to simulate this process numerically. Experimentally, an infrared thermography technique was used to measure the temperature distribution of the surface consisting of a 100 nm ITO layer on a ZnSe substrate. The heat flux was varied to investigate the heat transfer behavior of periodic droplet impingement at the solid–liquid interface. In both experiments and simulations, the morphology of the impact zone was characterized by a quasi-stationary liquid impact crater. Comparison of the radial temperature profiles on the impinging surface between the experiments and numerical simulations yielded reasonable agreement. Due to the strong radial flow emanating from successive droplet impacts, the temperature distribution inside the crater region was found to be significantly reduced from its saturated value. In effect, the heat transfer mode in this region was governed by single phase convective and conductive heat transfer, and was mostly affected by the HFE-7100 mass flow rates or the number of droplets. At higher heat fluxes, the minimum temperature, and its gradient with respect to the radial coordinate, increased considerably. Numerical comparison between average and instantaneous temperature profiles within the droplet impact region showed the effect of thermal mixing produced by the liquid crowns formed during successive droplet impact events.

A Study of the Heating Section of a Gas Heated Steam Reformer

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Margrete H. Wesenberg ◽  
Jochen Ströhle ◽  
Hallvard F Svendsen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fixed Bed ◽  
Two Dimensions ◽  
Fixed Bed Reactor ◽  
Discrete Ordinates ◽  
Temperature Profiles ◽  
Radial Temperature ◽  
Steam Reformer ◽  
Heating Section

A gas heated steam reformer (GHR) which converts natural gas to synthesis gas for methanol or Fischer-Tropsch purposes has been modelled for steady state conditions. The model is in two dimensions and is made up of a fixed bed reactor model, representing one of the reactor tubes in the GHR, and an annulus model, representing the annular space on the shell side of the GHR where hot, fully converted syngas emits heat to the reactor tube. The annulus model is described and evaluated in this article. This is a plug flow model which involves heat transfer in radial direction caused by radiation and by turbulence. The gas radiation is modelled by the use of the discrete ordinates method and the effect on heat transfer from turbulence is modelled as an effective radial thermal conductivity. Both heat transfer mechanisms vary with the radial position. An additional annulus model, made in the commercial CFD code FLUENT and based on the k-? turbulence model and the discrete ordinates radiation model, is used to estimate effective radial thermal conductivities. These were implemented in the annulus model of the GHR model. The reactor and the annulus models were combined and linked by the wall temperature profile and the heat flux profile on the outer reactor tube wall. The simulation results were used to study the heat flux and temperature profiles along the reactor length and the radial temperature profiles in the annulus.

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